Exemplary embodiments of the present invention are directed to an exterior module with an exterior panelling for a modularly constructed housing component and the modularly constructed housing component itself, and method for producing the exterior module
Specifically, exemplary embodiments of the present invention relate to a load-bearing exterior module of a motor vehicle with an exterior panelling for a modularly constructed housing component and the modularly constructed housing component itself, wherein this is in particular a door or trim component of a motor vehicle, and a method for producing the exterior module.
Modular motor vehicle doors or body trims typically have a three-part construction and comprise an interior module, to which an exterior module is applied on the outer side and a door interior is applied on the inner side. The exterior module can be designed to be self-supporting, in order to achieve improved handling and a simpler assembly of the module, but typically has no direct load-bearing function of the vehicle door.
The interior door trim and the panelling of the exterior module typically do not serve as a structural member in the event of a crash, instead in the majority of cases only the reinforcement regions of the interior module and the door frame or exterior module serve as crash structures. In this case, this can be a side-impact protection system that runs diagonally, such as is described in German patent document DE 10 2005 009 179 A1. Here, a motor vehicle door is disclosed, which has a lower weight so as to be applied more lightly during assembly and additionally has a higher level of crash stability. This motor vehicle door has an outer shell corresponding to the exterior module, having an exterior panelling, and an inner shell, which is formed by reinforcements that form narrow sides of the door. At least one support component for functional components is arranged on the inner shell on the inside. Here, the narrow sides of the door of the inner shell and the support component combine to form a single modular component that corresponds to the interior module, which modular component is provided with a separate interior door trim.
German patent document DE 10 2004 011 250 B3 discloses a releasable fastening of a plastic outer panelling to the door frame by means of rails and hooks. The exterior panelling of body components in modern motor vehicle doors typically is not involved in the increase in crash performance and, due to its lower levels of rigidity, requires additional stiffening elements. To that end, a particularly weight-optimal and rigid reinforcing structure for a side door of a motor vehicle is described in German patent document DE 10 2008 034 038 A1. This has a door support part for the door outer panelling and a reinforcing element for increasing the buckling resistance of the door in the vertical direction, at least above a partial height of the door. However, these stiffening elements are subsequently applied to the frame structure of the exterior module. These are necessary for, on the one hand, improving the buckling resistance in order to avoid minor damages and to produce a class-A surface, and on the other hand, for reducing the vibrational sensitivity of the large surface in order to prevent acoustic effects such as buzzing.
German patent document DE 10 2007 042 418 A1 describes a self-supporting exterior module that consists of a panelling applied to a load-bearing frame. The support structure is suitable for a simple assembly of the modules, but does not contribute as a structural component to the increase in crash performance.
The modular construction of motor vehicle doors is fundamentally a common method for reducing the operational and assembly efforts. The exterior panelling here mostly comprises only one door outer panel without structural tasks as a component of the motor vehicle body.
Modularly constructed body parts are disclosed in German patent document DE 10 2007 024 163 A1, wherein a panelling part produced from plastic is applied to a support structure made from steel or light metal. The support structure thus contributes to higher rigidity and strength and thus enables the class-A surface capability of the plastic panelling.
German patent document DE 202 20 552 U1 discloses a motor vehicle door with an exterior module and an assembly support. The exterior module has a door outer shell and forms an outer design surface of the motor vehicle door and the assembly support is arranged on the side of the exterior module allocated to a vehicle interior and can be connected to the exterior module; it bears electrical and/or mechanical functional components of the motor vehicle door. The exterior module has reinforcement regions in the region of its external edges, such that these possess a sufficient level of inherent rigidity and can be operated as a separate door element that is independent of the assembly support, which is only connected to the assembly support for the production of the complete motor vehicle door in a subsequent assembly step.
In the cited prior art, the panelling is not integrated into the body concept as a load-bearing component.
Exemplary embodiments of the present invention are directed to a load-bearing exterior module that has the exterior panelling, which provides an improvement in crash performance, satisfies acoustic and optical specifications and contributes to thermal insulation and weight reduction.
Exemplary embodiments of the present invention also relate to a modularly constructed housing component, in which the load-bearing exterior module is used accordingly.
Furthermore, exemplary embodiments of the present invention relate to the production of the exterior module of a motor vehicle with reduced investment and production costs, low dimensional tolerances and short cycle times is enabled.
A first embodiment of the exterior module with exterior panelling for a modularly constructed housing component has a multilayer construction that comprises an inner and an outer surface layer. An exterior skin is arranged on the outer surface layer, which forms the exterior panelling. Here, the inner surface layer is a thermoplastic FRP surface layer, which has stiffening elements on the side facing away from the outer surface layer, whereby the exterior module is formed as a load-bearing component. Thus, for example, it can be integrated into a modular body element and thus enables not only a high level of design freedom and functional integration, but also the adaptation of the crash-impinged panelling to the vehicle concept.
The housing component for which the exterior module is provided can therefore be a modularly constructed door or a trim component of a motor vehicle or of a device such as a household appliance.
Indeed, the exterior module of specific housing components can only have the described layer construction; the multilayer construction of the exterior modular will preferably have a structural core between the outer surface layer and the inner surface layer, which can consist of a foam material such as a polyurethane.
Alternatively or in addition to this, a honeycomb structure can be provided as the structural core. The structural core can have a variable thickness or a thickness that remains the same over the surface of the exterior module.
With this sandwich construction with a light core, a weight reduction of the exterior module, and thus the housing component, can be produced. The exterior module as a structural component enables the increase in crash performance by distributing the impact energy laminarly onto the support. Furthermore, the structural core serves to increase rigidity, wherein the progression of indentation resistance can be defined in a targeted manner over the indentation path by material selection, layer construction and functional elements.
In a further embodiment of the exterior module according to the invention, not only is the inner surface layer is a thermoplastic FRP but also the outer surface layer. As an alternative to a thermoplastic FRP surface layer as an outer surface layer, this can be formed on its own or together with the exterior skin by a pre-molded metal sheet, in particular aluminum sheet, or a pre-molded plastic part or by a plastic film or an SMC layer or a combination thereof.
Furthermore, the arrangement of such a pre-molded metal/aluminum sheet or plastic part or a plastic film or an SMC layer or a combination of these on an outer thermoplastic FRP surface layer is also conceivable.
In a preferred embodiment, the exterior skin is formed by an IMC layer, preferably made from a polyurethane. However, the exterior skin can also be formed by one (or more) lacquer layer(s) applied before or after the production of the multilayer construction.
In a suitable manner, the thermoplastic FRP surface layers can be simply formed from organic sheets, wherein these are plate-shaped, endless-fiber-reinforced thermoplastic semi-finished products, which have a reinforcing fiber arrangement in a thermoplastic matrix. Carbon fibers, glass fibers, aramid fibers, metal fibers or combinations thereof are preferably considered as reinforcing fibers. The fiber arrangements used often have orientated fibers and comprise cores, webs, meshes, knitted fabrics etc. A polyamide (PA), polypropylene (PP), polycarbonate (PC), polyphenylene sulphide (PPS), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polybutlyene terephthalate (PBT), or high-density polyethylenes (HDPE), for example, can be used as the thermoplastic matrix plastic.
The stiffening elements that have the inner surface layer can be reinforcing ribs that are injection-molded onto the inner surface layer. An injection-molded plastic suitable for this is compatible with the thermoplastic matrix plastic of the inner surface layer; the injection-molded plastic is preferably the same as the thermoplastic matrix plastic. The intermediate spaces existing between the injection-molded ribs can be foamed; to that end, a polyurethane can also be used. Furthermore, beadings can be introduced into the inner surface layer as stiffening elements or the inner surface layer can have undulating regions that serve to improve crash performance.
The sink marks potentially arising after the processing of the organic sheets when embodied with an outer thermoplastic FRP surface layer can be compensated for with a layer made from the thermoplastic matrix plastic, which is provided on the side of the outer thermoplastic FRP surface layer facing the exterior skin.
The outer and the inner surface layer of the exterior module can be connected to the border regions by folding over, welding or insert molding.
As well as the stiffening elements according to the invention, the inner surface layer can have openings and/or mold-injected contours and/or edges of border regions, clamping and/or fastening elements, in particular the latter for the fastening of the exterior module to an interior module of the modularly constructed housing component.
A modularly constructed housing component according to the invention consists of an exterior module according to one of the embodiments described, which forms an exterior panelling for the housing component and consists of an interior module connected to the exterior module.
Thus, an adhesive joint can be provided for the connection of the interior and exterior module. Alternatively or additionally, the inner surface layer of the exterior module can have an insertable section on the edge to be inscribed into the interior module, additionally or alternatively one or more tongues and or pins, which can be received in corresponding grooves or indentations of the interior module.
A method according to the invention for the production of an exterior module can be carried out by using a single tool consisting of two tool halves, the first of which is provided for the formation of the panelling on an external side of the external module and the other of which is provided for the formation of an interior of the exterior module. The tool possesses a specific sprue system for various plastics or plastic components, which allows the method to be implemented. In this case, first the inner and the outer surface layer are pre-molded according to the inner and outer external module contours and are then inserted into the corresponding tool halves. At least the inner surface layer is provided by a thermoplastic FRP surface layer. After the tool has been closed, a foam-forming material is injected between the surface layers by means of the sprue system of the tool and thus the structural core is formed as the foam core. Also, in the tool during the same closing cycle, the stiffening elements on the inner surface layer and the exterior skin on the outer surface layer are produced by means of the sprue system.
For the formation of the stiffening elements on the inner surface layer, the corresponding tool halves have corresponding mold cavities into which a suitable plastic is injected by means of a sprue device of the system, for example for the formation of ribs. The plastic that is compatible with or similar to the matrix plastic of the thermoplastic FRP surface layer enables a firmly bonded fastening of the injection-molded ribs.
The generation of the exterior skin on the surface layer preferably takes place by means of in-mold coating in the tool, wherein the tool is partially opened, and indeed as far as the layer thickness of the exterior skin requires, whereupon the outer surface layer is in particular coated with a polyurethane that is injected into the previously formed gap by means of a sprue device of the sprue system.
The pre-forming of the surface layers can, in the case of the thermoplastic FRP surface layers, take place simply by heating, in particular by means of infrared radiation, wherein the heated thermoplastic FRP surface layers can be molded and thus can be pre-formed by means of mold-adapted grippers, for example. The clamping of the surface layers by the grippers can take place by generating a negative pressure, in the same way as the fixing of the surface layers can also take place by generating a negative pressure during the insertion into the tool halves.
The “one-shot” method used for the production reduces the investment and production costs, guarantees low dimensional tolerances and enables short cycle times due to the use of a thermoplastic matrix system.
These and other advantages are demonstrated by the description below with reference to the accompanying figures. The reference to the figures in the description serves to support the description and to facilitate understanding of the subject matter. The figures are only a schematic depiction of an embodiment of the invention.